The present invention is in the field of piece goods conveying and generally concerns a method and device for splitting-up, according to a predetermined splitting-up sequence, a serial stream of piece goods being conveyed along a plurality of conveying away paths. More particularly, the method and device serve to split-up a stream of goods in which a large number of identical, or at least similar, objects (piece goods) are serially conveyed to form a plurality of different streams to be conveyed away. At the split-up point, the conveying path of the supply stream branches out in a plurality of conveying away paths and the objects are selectively guided onto one of the conveying away paths along which they are again serially conveyed onwards.
In the further processing of printed products, which is an example of an application for piece goods conveyance, conveyed streams can consist of printed products that are, for example, loosely lying on a conveyor surface (e.g., a conveyor belt). In such streams, the printed products usually overlap one another to define imbricated streams. Alternatively, such streams can consist of printed products that are held individually or in small groups by a gripper and conveyed behind each other in a hanging position. The grippers are installed on a conveying organ such as a conveyor chain, or else they are movable along a rail track more or less independently of one another. Such independent grippers are driven by corresponding drives, for example, by pushing one another along.
Shunt-like devices are usually employed for splitting-up imbricated streams of printed products. Devices of this kind are located at the split-up point and comprise a conveying support that is arranged between the feeder conveying support and the plurality of the conveying supports leading away. This conveying support swivels or is otherwise movable to selectively connect the conveying support of the feeder conveyor with one or another of the conveying supports leading away. Because the printed products in the imbricated stream overlap one another, it is necessary to provide, in addition to the swivelling conveying support, means for separating the imbricated stream, i.e. for locally cancelling the overlapping of the products for every changeover of the shunt. An example of an imbricated stream shunt is described, for example, in the publication EP-1063187.
For splitting-up a stream of printed products held individually or in small groups by supply system grippers, which are installed on a conveying organ, the printed products are selectively transferred to further conveyor systems, which, for example, also have grippers installed on conveying organs and designed for guiding the printed products away along the chosen path. Transfer points to a plurality of conveying away systems are usually arranged one behind the other along the supply track and, therefore, use up a lot of space.
In conveying systems, in which printed products are conveyed and held by grippers and in which the grippers are movable along a rail track independently of one another, points for splitting-up the conveyed stream are usually designed as rail junctions. Such points need to be equipped with control means for guiding the grippers from the supply rail to the desired rail leading away from the supply rail. In a conveying system comprising one or more splitting-up points of this type, provisions have to be made for the grippers, which are guided onto the various paths leading away, to be returned to a common point of departure. This means that return tracks have to be provided, which once again have to comprise shunts and joining points. Conveying systems of the named kind are described, for example, in the publications WO-98/03420 and WO-98/03419, a corresponding shunt in the publication WO-99/33720.
Also known are mixed forms of the above-described devices for splitting-up serial streams of piece goods.
An object of the present invention is to create a method and a device by means of which a serial stream of objects (piece goods) can be split-up into a plurality of further serial streams in which the objects are conveyed away. The splitting-up is to be controllable, for example, in accordance with a predetermined split-up sequence or by conditions further downstream or upstream and recorded by sensors. Alternatively, splitting-up is governed by a regular splitting cycle. At least the conveying away is to be a gripped conveyance, in which the objects are conveyed away and held, either individually or in small groups, by a gripper. The device according to the invention is to be simple, as universally utilizable as possible and, in particular, it shall be very space-saving.
In accordance with the method of the present invention, objects are serially conveyed toward a split-up point and, at the split-up point, they are positioned for being individually taken over by a holding means. For every object or small group of objects being positioned in the split-up point a holding means is supplied to the split-up point. This holding means belongs to the one conveying away system of the plurality of such systems, which defines the one leading away track on which the specific object or the specific group of objects is to be conveyed away. Therefore, holding means belonging to different conveying away systems are conveyed through the split-up point one after the other. For being supplied to the split-up point, the holding means are selectively released from buffers, which buffers also belong to different conveying away systems. Each one of the holding means supplied to the split-up point grips one of the positioned objects (or groups of objects) in order to convey it away from the split-up point along the leading away track of the conveying away system to which the holding means belongs.
The objects can be supplied with a regular or irregular spacing between them. A supply stream with an essentially regular spacing can also have gaps. Depending on the supply of the objects, holding means are supplied from the buffer of one conveying away system at the time to the split-up point either one per conveying cycle or selectively one or none (gap), or else just when required.
The device according to the invention comprises means for serially conveying objects to a split-up point and, at the split-up point, means for positioning the objects or groups of objects for being taken over by a holding means. The device further comprises a plurality of conveying away systems, wherein each of the conveying away systems comprises a rail track (advantageously being closed in itself) and a plurality of holding means movable along the rail track in the direction of conveyance. The rail tracks of rails of all conveying away systems advantageously converge or run parallel toward the split-up point, run parallel to one another and as close as possible to one another through the split-up point, and diverge after the split-up point.
As closely as possible upstream of the split-up point, each conveying away system comprises means for buffering holding means and means for a controlled release of holding means from the buffering means. Each conveying away system further comprises means for controlled conveyance of holding means through the split-up point and means for activating holding means in the split-up point for picking up an object. In order to be able to be buffered and to be recalled from the buffer in a controlled manner, the holding means of each conveying away system are movable independently of one another along the rail track of the conveying away system. Alternatively, the holding means are linked together with flexible means such that the spacing between adjacent holding means is variable.
In further accordance with the present invention, the device includes control means for coordinating the recall of the holding means from the buffer such that the serial stream of holding means conveyed through the split-up point comprises a sequence of holding means belonging to the various conveying away systems, which sequence corresponds to a required split-up sequence.
Because for every conveying away of an object only one holding means of one of the conveying away systems is released and transported through the split-up point, the holding means conveyed through the split-up point form a serial stream. In this stream the holding means can readily be conveyed on conveying paths, which are partially overlapping or identical. This means that even when the rail tracks of the conveying away systems run through the split-up point with minimum distances between each other there are no unwanted collisions during the transportation through the split-up point because of the serial release of the holding means from the various buffers. Neither are there undesirable simultaneous interactions of several holding means with a single object.
In the serial stream of holding means through the split-up point, the holding means have a spacing between one another, which is matched to the spacing between the supplied objects. This spacing can, therefore, be regular or irregular (also substantially regular, but with gaps).
Advantageously, the rail tracks of the conveying away systems pass through the split-up point as close to one another as possible. In this manner, during the taking-over of the objects, the positions of the holding means of different conveying away systems relative to the position of the objects to be taken over manifest as little difference from one another as possible. In such cases, where it is necessary for all objects to be picked up by the holding means in the same zonexe2x80x94independent of the path they are to be conveyed away onxe2x80x94, the following solution is provided: depending on which conveying away system is to take over an object, a rail track, a holding means, the object to be taken over, or the supply system or a part thereof is designed to be displaceable perpendicular to the general direction of conveyance in the area of the split-up point. It is also possible to design the holding means of the various conveying away systems correspondingly differently, such that their position relative to their rail track is different.